HAYATI Journal of Biosciences, December 2009, p 135-141 Vol. 16, No. 4ISSN: 1978-3019

Encapsulation and Hemocyte Numbers in Crocidolomia pavonana andSpodoptera litura Fabricius (Lepidoptera) Attacked by Parasitoid

Eriborus argenteopilosus Cameron (Hymenoptera)

DAMAYANTI BUCHORI1∗∗∗∗∗, BANDUNG SAHARI2, ENDANG SRI RATNA1

1Department of Plant Protection, Bogor Agricultural University, Jalan Kamper, Dramaga Campus, Bogor 16680, Indonesia2Peka Indonesia Foundation (Indonesian Nature Conservation Foundation), Jalan Uranus Blok H No. 1,

Sindang Barang, Bogor 16680, Indonesia

Received March 11, 2009/Accepted December 15, 2009

Eriborus argenteopilosus is the most important parasitoid attacking cabbage pest Crocidolomia pavonana in Indonesia.Previous studies proved that parasitoid encapsulation was found to be an important factor limiting the effectiveness of theparasitoid in controlling pest population in the field. Since 1998, we have conducted series studies to investigateencapsulation mechanism developed by hosts against parasitoid, responses of parasitoid toward encapsulation ability andto determine factors that may help parasitoid avoid encapsulation. Parasitoid responses were examined on two differenthosts C. pavonana and Spodoptera litura. Our findings showed that parasitization level was found to be high both onC. pavonana and S. litura. Encapsulation occurred to be high in all larva stages of C. pavonana, in contrast encapsulationwas recorded very low in all larvae stages of S. litura. We recorded that encapsulation in the larval body of C. pavonana wascompleted in 72 hours and mostly occurred in higher larval stage. Melanization was only recorded in encapsulatedparasitoid inside larva body of C. pavonana, not in S. litura. We recorded that encapsulation increased blood cell numberof both larvae C. pavonana and S. litura. Encapsulation may affect development of immature parasitoid. Weightof S. litura’s pupae containing encapsulated parasitoid was found to be lower in S. litura, but not in C. pavonana. Ourinvestigation also proved that superparasitism may help parasitoid avoid encapsulation.

Key words: parasitoid, encapsulation, melanization, blood cell number, superparasitism___________________________________________________________________________

INTRODUCTION

Encapsulation has been envisaged as one factorcontributes to the failure of parasitoid’s work in controllingpest population in the field (Hadi 1985; Goodfray 1994;Blumberg 1997; Sagarra 2000; Alleyne & Wiedenmann 2001).Encapsulation is widely defined as a common and an activephysiological defense mechanism that is an immune responseof the host against the intrusion of an external element, suchas eggs of parasitoid and other foreign organism insertedinto the host haemocol (Godfray 1994; Strand & Pech 1995;Pech & Strand 1996; Blumberg 1997; Quicke 1997; Chapman1998; Sagarra et al. 2000). The successful development of animmature endoparasitoid is strongly influenced by host’sdefense system and the parasitoid’s ability to evade thesystems. Encapsulated parasitoid may be die by suffocation,starvation, or physical prevention of development (Blumberg1997). Encapsulation involves host hemocytes that recognizethe invader as non-self, subsequent of more hemocytes, andadherence of hemocytes to the invader’s survace, eventuallyresulting in a multicellular capsule that kills the parasitoids(Godfray 1994; Pech & Strand 1996; Alleyne & Wiedenmann2001). Partial encapsulated parasitoid may survive andcontinue to grow normally (van den Bosch 1964).

Encapsulation was reported to occur in many species ofinsect, such as in three families of Coccoidea (Homoptera),Coccidae (Soft scale insects), Diaspididae (armored scaleinsect), and Pseudococcidae (mealybugs) (Blumberg 1997;Blumberg & Driesche 2001), in Hypera postica (Coleoptera:Curculionidae) ( Berberet et al. 2003), and in Drosophila (Nappi1975; Rizki & Rizki 1984). Sagarra et al. (2000) reported thatthe hibiscus mealybug, Maconellicoccus hirsutus developsa cellular defense reaction that involves encapsulation andmelanization of the endoparasitoid egg Anagyrus kamali(Encyrtidae). Encapsulation was also recorded in threeLepidopteran stemborers attacked by Cotesia flavipes-complex endoparasitoids (Alleyne & Wiedenmann 2001).

Eriborus argenteopilosus is the most important parasitoidattacking cabbage pest Crocidolomia pavonana in Indonesia.The parasitoid was also reported to attack several hosts suchas Helicoverpa armigera (Kalshoven 1981), Spodopteralitura, and Spodoptera exigua. Hadi (1985) reported thatencapsulation was found to be the most important factorlimiting parasitoid’s capability in controling the cabage pestin the field. Unfortunately, up till today, in Indonesia no studyhas ever been conducted to evaluate how encapsulationdevelops and works against parasitoid invasion and how isthe response of parasitoid toward encapsulation ability. Theobjectives of the research were to explain encapsulationprocess and its impact on parasitoid immature development,

_________________∗∗∗∗∗Corresponding author. Phone: +62-251-8425980,

Fax: +62-251-8629362, E-mail: dami@indo.net.id

Copyright © 2009 Institut Pertanian Bogor. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

to identify its effects on number of blood cells of parasitizedhosts, and to study the parasitoid’s counter measures to avoidencapsulation (e.g supperparasitism).

MATERIALS AND METHODS

Rearing of Hosts C. pavonana and S. litura. LarvaC. pavonana was collected from cabbage plantations inCianjur and S. litura was from soybean plantations in Bogor.Larvae were then brought into the laboratory for rearing.Larvae were maintained inside a plastic box ( 35 x 25 x 7 cm3 ).In order to facilitate air circulation, plastic boxes were equippedwith mesh window (25 mesh). One plastic box is only allowedto contain the same stage of larvae from the same species.Larvae which are getting pupation were removed into a plasticcontainer containing sterilized wood dust and thosecontainers were placed inside adult wood cages (40 x 40 x40 cm3). Emerged moths were than removed into adult cagesand maintained with honey sollution (10%). Soybean leaf wasplaced inside the adult cages for oviposition. The same rearingtreatment by using broccoli leaf was also applied for C. pavonana.Eggs laid by female moth were collected and incubated underroom temperatur. Emerged larvae were used for experimentaltest and rearing.

Rearing of the Parasitoid E. argenteopilosus. ParasitoidE. argenteopilosus were collected by using sweep net fromcabbage plantations in Cianjur, West Java. The adults werereared by exposing mated female on its host C. pavonana orS. litura inside the rearing cages for 24 hours. Parasitizedhosts were then separated from female parasitoid and removedinto a plastic box (35 x 25 x 7 cm3). Parasitized hosts weremaintained by using broccolli leaf until pupation. Emergedparasitoids were collected 8-9 days after pupation. Two-daysold, mated females were used for experiment and for rearingpurpose. Female parasitoids were considered experienced asthey had been exposed upon emergence to different stagesof host in the rearing cages for 24 hours.

Experimental Procedure. In prelimary test, two species ofthe parasitoid’s host C. pavonana and S. litura were used.All immature stages of C. pavonana and S. litura were tested,however L4 and L5 of S. litura were not suitable for ovipositionsince their size are too big for parasitoid to attack. In thisexperiment, only active and normal parasitoid allowed to beused for oviposition. All tests were conducted under roomtemperature (27-30 oC ).

Parasitization Tests. Parasitization test was conductedby exposing mated active female parasitoid on 20 larval of C.pavonana and S. litura. All larvae stages of C. pavonanawere used for parasitization test (L1-L4), in the other side,only L1-L3. (1st instar) of S. litura were used. Higher stages ofS. litura larvae were not suitable for parasitization due tohigher size. Larvae were exposed on parasitoid for 24 hours,and then all larvae were dissected individually to count theparasitization level.

Encapsulation Ability of Two Hosts C. pavonana andS. litura. To evaluate encapsulation ability of two differenthosts, approximatelly 25 larvae were directly exposed on activefemale parasitoid. Parasitized larvae were removed from the

parasitoid and were maintained under laboratory conditionfor 72 hours. All parasitized larvae were dissected underbinocular microscope and number of hosts containingencapsulated parasitoid were counted as a measurementhost’s capability in encapsulating parasitoid. All examinationwas set up for 10 replications.

Response of Host Immune Againsts Parasitoid:Chronology of Encapsulation Dissections. Twenty larvae ofS. litura and C. pavonana were exposed individually on activefemale parasitoid under transparent glass tube (t = 20 cm, d =3 cm) and after oviposition, hosts larvae were then removedand placed into plastic containers (t = 20 cm, d = 9 cm). Theparasitized hosts were maintained with broccoli leaf for rearinguntil dissection. On each day that hosts were parasitized,randomly selected hosts were assigned to different time pointsat which they would be dissected. Both of host species werethen dissected in a drop of ethanol (70%) at 0, 3, 6, 12, 18, 24,48, 72, 96, 120, 144, and 198 h after removal of the parasitoidsto observe the dynamics of the immature parasitoidencapsulation. However, different larvae stages or species,will be suitable for different dissection period since older hostsneed shorter time to get pupation. Dissection will only beallowed to be conducted before hosts getting pupation. Ateach time interval, a total of 10 hosts of each stage and eachspecies were dissected. Number of hosts containingencapsulated parasitoid were recorded and size of immatureparasitoid were measured to determine the development ofimmature parasitoid.

Total Hemocyte Counts. Second Larvae (L2) of S. lituraand C. pavonana were individually exposed to the activefemale parasitoid. After parasitization larvae were placed intoplastic container with brocolli leaf and were observed dailyuntil the scheduled assay time. One cohort consisted of 20parasitized larvae and 20 control larva at the same age.Hemocyte numbers were determined at 3 and 5 days afterparasitization. Hemolymph from a parasitized larvae wasassayed at the same time as the hemolymph of unparasitizedcontrol larvae of exactly the same age. Hemolymph wassqueezed from a cut proleg by using micropipette for 10 µl.Hemolymph was soluted with buffer chloride phosphat 1:10(0.15 M NaCl, 5 mM KPO

4, pH 6.5) and was transferred with

micropipettte to the Neubauer hemocytometer (Stoltz & Guzo1986). The treatment was set up for 10 replications.

Effects of Encapsulated Parasitoid on the Weight ofSurvived Host’s Pupae. First and second larvae of C.pavonana and S. litura were individually exposed toovipositing E. argenteopilosus as previously described. Allparasitized hosts then were maintained under laboratorycondition. The parasitized larvae were observed daily andnumber of survived pupae were recorded. At least 10 survivedpupae were balanced. In this test, weight of survivedparasitized pupa and unparasitized pupae were measured.

Data Analyses. Statistical analyses of the data wereperformed using the software Statistica for Windows 6.0(Statsoft 2001). Pearson’s correlations were conducted whendata proved to be normally distributed, otherwise Spearmanrank correlations were used (Sokal & Rohfl 1995). Analysis ofvariance (ANOVA) was used to test for differences between

136 BUCHORI ET AL. HAYATI J Biosci

two or more groups. Differences between means were testedfor significance by the Scheffe’ test at (P = 0.05).

RESULTS

Parasitism Rate of Parasitoid E. argenteopilosus underLaboratory Condition. Parasitization represents the ability ofparasitoid in controling its hosts under laboratory condition.Parasitization E. argenteopilosus on its host C. pavonanaranged between 27-50% (+ 67.70%) in L1, 50-100% (+ 78.96%)in L2, 5-77% (+ 52.91%) in L3, and 0-41% (+ 24.88%) in L4. Ouranalyses identified that parasitization was significantlyaffected by growth phase of host (F

3,36 = 12.34; P < 0.0001, n =

40). Parasitization level was recorded to be lower in the olderstage compared with the younger one (Figure 1). This wasalso confirmed by conducting Spearman rank correlationbetween larval stages and parasitization. Significant negativecorrelation was found between those parameters (Spearmanrank correlation: n = 40, R Spearman = -0.59, P < 0.0001),parasitization level decreases with increasing larval stages(not shown). In contrast, we did not find that growth phase

affected the parasitization of the Parasitoid on Spodopteralarva (F

2,27 = 0.18; P = 0.835, n = 30).

Encapsulation Capability of C. pavonana and S. litura.Number of larvae containing encapsulated immatureparasitoid was recorded to be higher in C. pavonanacompared with S. litura. Encapsulation reached more than 80percent in C. pavonana, conversely, encapsulation wasrecorded under 15 percent in all tested larval stages of S.litura. Number of larvae containing encapsulated immatureparasitoid was significantly affected by host stage both in C.pavonana (F

2,27 = 26.90, P < 0.0001, n = 30) and in S. litura

(F2,27

= 10.25, P < 0.0005, n = 30). Older stages were recorded tohave a higher capability in parasitoid encapsulation than theyounger stages. Number of larvae C. pavonana containingencapsulated parasitoid was found to be lower in L1 comparedwith L2 and L3. Similar result was also documented for S.litura, number of larvae containing encapsulated parasitoidwas found to be lower in L1 and L2 than the older stage(Figure 2).

Host Immune Response. Encapsulated immature parasitoid(larva or egg) can be clearly observed in the larvae body of C.

Par

asit

izat

ion

(%)

Larva stage of C. pavonana

Par

asit

izat

ion

(%)

Larva stage S. litura

Figure 1. Parasitization level of Parasitoid E. argenteopilosus on itshosts C. pavonana and S. litura in different growth phases.

: + Std. Dev, : + Std. Err, : Mean.

Hos

t co

ntai

ning

enc

apsu

late

d pa

rasi

toid

(%

)H

ost

cont

aini

ng e

ncap

sula

ted

para

sito

id (

%)

Host stages of C. pavanana

Host stages

Figure 2. Number of larvae containing encapsulated parasitoid in C.pavonana and S. litura. : + Std. Dev, : + Std. Err, :Mean.

Vol. 16, 2009 PARASITISM AND ENCAPSULATION OF ERIBORUS ARGENTEOPILOSUS IN LEPIDOPTERAN HOST

137

pavonana. The indication of immature parasitoidencapsulation was recorded from the formation of accumulatedcircle materials surrounding the object shaping a ring-likewhose color changed gradually from transparent to yellowish-brown (amber). Encapsulation proccess continued by initiationof capsule shape from aggregates of melanized material whichformed spots that gradually spread over the entire immatureparasitoid surface. In this phase, capsule covering the objectcompletely. Finally, multicellular capsule-like envelope coatingthe object was formed. The size of the melanized capsuleincreased with increasing periode of time.

The process of encapsulation inside the larva body of C.pavonana was started by the formation of circle materialsspread over shaping a ring enclose the immature parasitoid.This initiation was started in different period of time for differentlarval stage. In L4, the initiation was started three hours aftereggs oviposited by female parasitoid. In contrast, in L2/L3,the process can be observed about 18 hours after ovipostion.The number of circle materials increased with increasingperiode of time, forming aggregate materials enveloping theimmature parasitoid. The color of encapsulated material wasgradually changed from transparent to amber. Melanizationwas recorded after the formation of multicelullar capsule-likeenvelope completed. The color of melanized material graduallychanged from light-yellow into dark orange. Encapsulatedparasitoid become a smaller material in the post-encapsulation.In the larvae of S. litura, melanization was not recorded andparasitoid encapsulated was rarely found.

Initiation of encapsulation process vary for different hostspecies, larval stages, and individu of the same host. Initiationof encapsulation can be observed anytime wether at egg stageor larval stage of immature parasitoid. Partial encapsulationcan obviously be found only when encapsulation was initiatedat the larval stage. Number of encapsulated parasitoidincreased with increasing period of time and reaching thepeak 72 h after oviposition. Approximatelly, 90% imatureparasitoid inside the larva body of L2 and L3 was encapsulated,and only 50% recorded for L1 in this dissection period (Figure3). Encapsulated parasitoid decreased in size and becomesmaller or very smaller dead material. Number of encapsulatedparasitoids decreased after dissection period for 72 h.

Effects of Encapsulation on the Development of ImmatureParasitoid: Host Stage or Species? Body length of immatureparasitoid developed inside L1’s body was recorded to behigher than in older stages of host. This can be clearly seenafter parasitoid eggs hatched and developed become younglarvae (48 h after oviposition). Development of parasitoid eggsize (before 24 h), did not prove to be significant between L1,L2, and L3. In contrast, larvae size was recorded to be higherin L1 than in older stages, at the dissection periods of 48 and72 h after oviposition (Figure 4). The development of bodylength of immature parasitoid was found to be higher in L1 ofC. pavonana than in S. litura, conversely, in L2, body lengthsize of immature parasitoid was recorded to be higher in S.litura than in C. pavonana (Figure 5).

Hemocyte Numbers. Number of blood cell was recordedto be higher in parasitized larvae than unparasitized larvae ofboth C. pavonana (Day-3: F

1,18 = 19.97, P = 0.0003, n = 20;

Day-5: F1,18

= 18.09, P = 0.0005, n = 20), and S. litura (Day-3:F

1,18 = 7.62, P = 0.013, n = 20, Day-5: F

1,18 = 18.17, P = 0.0005, n

= 20). Increasing period of time was followed by increasingnumber of blood cells. Number of blood cell involved in theresponse of host toward parasitoid invasion was found to behigher in larvae C. pavonana than S. litura (Figure 6).

Effects of Encapsulated Parasitoid on the Weight (gr) ofSurvived Host’s Pupae. Parasitized larvae which have canresist parasitism may survive to grow until pupae. Effects ofencapsulated parasitoid on weight of survived pupae can be

Enc

apsu

late

d im

mat

ure

para

sito

id (

%)

Time after oviposition (h)

Enc

apsu

late

d im

mat

ure

para

sito

id (

%)

Time after oviposition (h)

L1 = -21.659 + 29.032*log10(x)+epsL2 = -31.057 + 52.279*log10(x)+epsL3 = -51.628 + 65.981*log10(x)+epsL4 = -5.936 + 41.439*log10(x)+eps

L1 = 0 + 0*log10(x)+epsL2 = -2.798 + 4.175*log10(x)+epsL3 = -3.257 + 4.472*log10(x)+eps

Figure 3. Percentage of encapsulation of immature stage of E.argenteopilosus as a function of time.

Bod

y le

nght

(m

m)

Time after oviposition

Figure 4. Body length (mm) of immature parasitoid inside larva bodyof L1, L2, and L3 C. pavonana in different period of time.

138 BUCHORI ET AL. HAYATI J Biosci

Bod

y le

nght

(m

m)

Time after oviposition

Bod

y le

nght

(m

m)

Time after oviposition

Figure 5. Body lenght of immature parasitoid inside L1 and L2 of C.pavonana (C) and S. litura (S).

Num

ber

of b

lood

cel

ls

Time after oviposition (C. pavonana)

Num

ber

of b

lood

cel

ls

Time after oviposition (S. litura)

Figure 6. Number of blood cell of parasitized and unparasitized larvaethree days and five days after oviposition. � : parasitizedlarvae, �: unparasitized larvae.

Table 1. Weight (gr) of parasitized and unparasitized pupae of C. pavonana and S. litura

L1 L2 Parasitized Unparasitized Parasitized UnparasitizedHosts

Crocidolomia binotalisSpodoptera litura

0.0375 + 0.004a0.1001 + 0.0662a

0.0346 + 0.007a0.2106 + 0.0359b

0.0415 + 0.004a0.1087 + 0.0384a

0.0408 + 0.006a0.2256 + 0.0341b

Table 2. Number of eggs laid by female parasitoid in superparasitimincidence inside the larval body of C. pavonana

Mean number of Mean number of survived eggs laid by female immature parasitoid parasitoid per hosts after 72 hStage

Superparasitism(%)

71.79 + 29.85a68.15 + 19.17a62.38 + 24.01a

2.11 + 0.84a2.31 + 0.88a2.13 + 0.66a

0.77 + 0.64a0.36 + 0.53a0.64 + 0.97a

L1L2L3

observed by comparing the weight of pupae betweenunparasitized and parasitized pupae. There was no significantdifferent found between weight of parasitized pupa andunparasitized pupae of C. pavonana (L1: F

1,18 = 1.22, P = 0.284,

n = 20; L2:F1,18

= 0.105, P = 0.749, n = 20). In contrast, significantdifferent was recorded between parasitized pupae andunparasitized pupa of S. litura (L1:F

1,18 = 51.997, P < 0.0001,

L2:F1.18

= 21.56, P = 0.0002) (Table 1).Does Superparasitism Contribute to Avoid Parasitoid

Progeny from Encapsulation? Superparasitism was recordedto be occurred on female parasitoid E. argenteopilosus on itshost C. pavonana. Superparasitism was occurred in a highrate between 62 and 72% in average. Statistical analyses did

not find a significant different between L1, L2, and L3 withrespect to superparasitim occurrences (F

2,27 = 2.22, P = 0.127,

n = 30). Number of eggs observed per host individual rangedbetween 1 and 5 eggs, with average of about 2 eggs per host.Mean number of eggs laid by female parasitoid per host wasnot significant between larval stages. (F

2,27 = 1.167, P = 0.327,

n = 30). In the superparasitized host, at least, we can find oneegg escape from encapsulation mechanism developed byhost. Mean number of survived immature parasitoid after 72 hwas not recorded to be significant between larval stages (F

2,27

= 0.77, P = 0.47, n = 30) (Table 2).

Vol. 16, 2009 PARASITISM AND ENCAPSULATION OF ERIBORUS ARGENTEOPILOSUS IN LEPIDOPTERAN HOST

139

DISCUSSION

The capability of parasitoid in controling its hosts can beobserved from the parasitization level. This research provedthat parasitoid E. argenteopilous has a high capability incontroling its hosts, this can be seen from a high percentageof parasitization on its two hosts C. pavonana and S. litura.Encapsulation as a host defense mechanism may confine theeffectiveness of parasitoid in suppressing pest population inthe field (Hadi 1985; Blumberg 1997; Sahari 1999; Sagarra 2000;Alleyne & Wiedenmann 2001). Previous studies identifiedthat the failure of the parasitoid in controlling C. pavonanain the field may be related to encapsulation mechanismdeveloped by the host (Hadi 1985). This study confirmedthose findings that C. pavonana has a high capability inencapsulating immature parasitoid inserted by femaleparasitoid. Encapsulation of inserted immature parasitoid wasrecorded in all stages. However, with respect to encapsulation,the effectiveness of parasitoid may depend on host species.This study found that encapsulation was rarely found in otherhost species S. litura. Encapsulation was recorded to be veryhigh in younger larvae and this mechanism can be observedearlier in the older stages. This may be related to the vigor ofhost both physiologically and physically. Older hosts mayhave a stronger immune response and better fitness thanyounger hosts (Godfray 1994). This was confirmed by Saggaraet al. (2000) who reported that older stages of host have amature immune system to encapsulate parasitoid.

Encapsulated parasitoid can be recognized by theformation of melanized material aggregates surrounding theimmature parasitoid (Sagarra et al. 2000; Reed et al. 2007).The process of encapsulation involves many types of bloodcell which work in recognizing and encapsulating invadingobjects (Gupta 1991; Chapman 1998). Encapsulation will startwhen granullar cells recognize and attached to the foreigntarget (Pech & Strand 1996). In the process of cellularencapsulation, the host’s blood cell forming a multicellularcapsule-like envelope around invading parasitoids (Blumberg1997). In General, encapsulation is started 24 h afteroviposition (Woodring 1985; Chapman 1998; Reed et al. 2007).In this study, initiation of encapsulation was related to hoststage and host species. In L4 of C. pavonana, encapsulationcan be observed only three hours after oviposition,conversely, in L2/L3 encapsulation can be detected between18 and 24 hours after oviposition. In S. litura, encapsulatedparasitoid can be recognized 48 hours after oviposition.Encapsulated parasitoid may die by suffocation, starvation,or physical prevention of development, however partialencapsulation may allow parasitoid continue to grow normallyuntil pupa (Blumberg 1997).

Encapsulation may also has an effect on the developmentof immature parasitoid (Blumberg 1997). This was alsoconfirmed by the result of the study. Body length of immatureparasitoid developed inside L1’s body was recorded to behigher than in older stages of host. This study also recordedthat encapsulation in L1 was noted to be lower than olderstages, and encapsulation process can only be observed after

parasitoid egg hached into larva. This situation provided anadvantage for immature parasitoid continue to grow. Previousfinding documented that parasitoid may avoid encapsulationby active movement of encapsulated larvae (Woodring 1985;Chapman 1998). Sagarra (2000) reported that Anagyruskamali, attacking the hibiscus mealybug, Maconellicoccushirsutus, may evade encapsulation by ovipositing its eggs inearly stages of hosts in which the immune system is not yetmature and unable to elaborate a significant defense. Olderstages were documented to have a sufficiently developedimmune system to effectivelly encapsulate the parasitoideggs.

Haemocytes play an essential role in defending insectagainst parasites invading their haemocol (Pech & Strand1996). Encapsulation is formed and performed by the bloodcell of the host, therefore it is only effective againstendoparasitoid which oviposit their eggs and develop withinthe host’ body (Blumberg 1997). Effects of encapsulation onthe host’s haemosyte were documented by many studies(Strand & Noda 1991; Alleyne & Wiedenmann 2001). Numberof blood cell was recorded to be higher in parasitized larvaethan unparasitized larvae of both C. pavonana and S. litura.Similar result was also recorded for parasitized larvae ofPseudoplusia includens attacked by Microplitis demolitor(Strand & Noda 1991). Increasing period of time was followedby increasing number of blood cells. This finding suggeststhat number of blood cell increases at the older stage of host.Many studies identified that number and types of blood cellwere found to be lower in young stage than in older stages(Gupta 1991; Chapman 1998). Number of blood cell involvedin the response of host toward parasitoid invasion was foundto be higher in larvae C. pavonana than S. litura.

Parasitized larvae which have a high capability ofencapsulation may survive to grow until pupae. The questionis can survived host’s pupae grow normally? Effects ofencapsulated parasitoid on weight of survived pupae can beobserved by comparing the weight of pupae betweenunparasitized and parasitized pupae. Our findings indicatedthat weight of survived pupae of S. litura was lower thanunparasitized pupae. This suggests that there is a possiblerelationship between encapsulated parasitoid and the survivalof host. In contrast, we did not find a significant differentbetween parasitized and unparasitized pupa of C. pavonanawith respect to pupae’s weight. Relationship betweenencapsulated parasitoid and the survival of host wasconfirmed by Fellowes et al. (1998) who found that pupaedeveloping from larvae that have encapsulated the parasitoidAsobara tabida are smaller and have relatively thinner puparia.Thinner puparia are likely to be associated with a reduction inmechanical strength and possibly with a decrease indesiccation tolerance. They also mentioned that fecundityand size of adult Drosophila melanogaster emerged from pupathat have encapsulated its parasitoid was reduced.

Superparasitism was documented to be one factor mayhelp parasitoid avoid encapsulation (Sagarra 2000).Superparasitism was also recorded to be occurred on femaleparasitoid E. argenteopilosus on its host. Superparasitism

140 BUCHORI ET AL. HAYATI J Biosci

may increase the probabilities of survival of parasitoidprogeny with respect to encapsulation (Sagarra 2000). Ourfindings identified that at least there was one immatureparasitoid survive from encapsulation in the superparasitismoccurrence. This result was recorded to be similar with Sagarra(2000), who reported that supperparasitism helped A. kamaliin avoiding encapsulation, immune system of host wasexhausted by high level of superparasitism.

Further research are needed to look at the possibility todecrease encapsulation rate by hosts. This step is veryimportant to develop strategy that can enhance theeffectiveness of E. argenteopilosus in controling C.pavonana.

ACKNOWLEDGEMENT

We thank the RUT VII, Ministry of Research andTechnology and Wildlife Trust for funding the research. TheRUT VII was given to D. Buchori. We thank to Yusuf and ReniKrisnawati for technical assistance, Bogor AgriculturalUniversity.

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